Page 13 of 23
DWG ID: 181-0101-01
Date: 2003-08-12
6 ADDITIONAL INFORMATION FOR A1 ASSEMBLIES
The A1 assembly is made from the A1A1 circuit card assembly Ritron radio transceiver.
6.1
Internal Adjustments
Note:
All internal adjustments for optimum performance have been performed at Ritron’s
factory. These adjustments should not be changed unless one is fairly certain alignment is
necessary, or repairs have been made to appropriate sections of the CCA. In order to
effect adjustments you will need to prepare a cable assembly to go between the Controller
CCA and the radio transceiver CCA, so the Controller CCA can be swung out of the way
in order to gain access to the radio transceiver and still be connected to it.
6.1.1
Front-end Inductors
Front-end inductors
•
L101 – L106 on the Ritron DTX-454-OBN6-DD UHF radio
•
L102 – L104 and L107 – L109 on the Ritron DTX-154-OBN6-DD VHF radio
are factory-preset for optimum sensitivity across the band of frequencies for each model.
These inductors should never need adjustment unless a component in the front end is
replaced, and even then, adjustment should not be necessary. If adjustment is desirable,
adjust the slugs for maximum sensitivity at mid-frequency, then check the band edge
frequencies. If the sensitivity is worse by 1 dB or more, each slug should be adjusted
slightly to test for improvement. Only those slugs, which improve the sensitivity, should
be changed and only by an amount necessary to bring the sensitivity within 1 dB of the
mid-frequency. After any change is made, recheck sensitivity across the band. You may
have to repeat adjustments several times to achieve satisfactory performance.
6.1.2
VCTCXO Frequency Adjust
The frequency of the VCTCXO (Y101) is controlled by dc voltage on its tuning pin and
by adjustment of the trimmer capacitor accessible through a hole in the top of the
VCTCXO itself. Tuning sensitivity through the electronic control pin is much greater
than that of the trimmer capacitor. The trimmer capacitor is normally never adjusted,
even at the factory. If, however, the TX and RX Frequency Trim values are approaching
the limits of the electronic adjustment, adjustment of the trimmer capacitor may help
bring trim values toward the center.
6.2
Active Component Voltage Chart for DTX-454 RF CCA
Note:
All voltages measured with reference to negative supply input (case ground).
